In a large soup pot, bring 5 cups of water and 5 cups of vegetable stock to a boil with quartered beets. Cook on medium heat, a simmer, until beets are fork tender. This takes about 20-30 minutes. After the beets are cooked add lemon juice, salt, pepper, and potatoes, and a splash of apple cider vinegar and cook for another 10 minutes until the potatoes are tender then take off the heat. Put the pot of soup into the refrigerator to chill for at least 2 hours. Carefully transfer the soup to a high-speed blender in small amounts to blend half the mixture at a time or you can use an immersion blender in the soup pot. Blend the soup until it’s creamy. OR keep chunky if so desired. To serve, add chilled borscht into bowls and garnish with optional toppings, (sour cream, coconut yogurt, avocado. I like to add pinches of parsley or cilantro for garnish). Store in an airtight glass container for up to 1 week.